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DER

Sensibly equivalent to:
POVT33
See also:
DER Valves - In the Beginning - Osram - Some Important British Valves - Marconi DER Advert - Marconi R & DER Advert - Marconi DER Advert - Marconi DER Advert
    
Extras ▼

 

This exhibit is an early DER triode. The thoriated tungsten filament and the planned use in receiving gave the valve its name - Dull Emitting Receiving.
Visual inspection shows that the anode cylinder of this valve is vertical within the envelope and this was the earliest form of the DER construction. However, the electrodes were prone to vibration and the valve thus became microphonic. To remove this problem the traditional horizontal construction was used for later production.
The balloon envelope is 48 mm in diameter and, excluding the B4 base pins, is 100 mm tall.
Reference: 1003. Type DER was first introduced in 1921.

 

Pin Connections
B4
1
2
3
4
a
g1
f
f

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
μ
1.8
0.35
80
-3
-
32,000
0.28
9.0
Updated July 31, 2015.
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